A new family of high-affinity ABC manganese and zinc permeases

Phylogenetic analysis of 47 extracellular putative metal binding receptors (MBRs) belonging to the newly defined cluster suggests the existence of two subclusters. The question of substrate specificity of the corresponding AT P binding cassette (ABC) permeases is discussed, based on data collected fr om 19 of them concerning their regulation, metal requirement of permease mu tants, metal uptake and metal binding. The proposal that the two subcluster s correspond to paralogous metal permeases dedicated primarily to manganese and to zinc transport is made. The question of a direct role of MBRs as ad hesins of Gram-positive bacteria is then discussed and the importance of me tal permeases for cellular processes and host-bacteria interactions is revi ewed. (C) 2001 Editions scientifiques et medicales Elsevier SAS.